In a magnetic recording method, high recording density causes the magnetic bit to be seriously susceptible to ambient temperature and other factors. This requires use of a recording medium having a greater coercive force. However, use of such a recording medium, in turn, increases the magnetic field required recording. The upper limit of the magnetic field generated by the recording head depends on the saturation magnetic flux density. This value, however, has already come very close to the limit of the material, and a drastic increase cannot be expected. A solution to this problem is proposed in a technique where magnetic weakening is caused by local heating at the time of recording, and recording is performed when the coercive force is reduced, and heating is then suspended to cause natural cooling, thereby stabilizing the recorded magnetic bit. This technique is referred to as a heat-assisted magnetic recording system.
In the heat-assisted magnetic recording system, the recording medium is preferably heated instantaneously. Further, a heating device is not allowed to be in contact with a recording medium. Thus, it is a common practice to use absorption of light for heating. This method of using light for heating is referred to as an optically assisted magnetic recording method. The head that uses light to record on the recording medium is commonly called the optical recording head.
In order to levitate the optical recording head above the recording medium by force of air, the optical head has, on the surface opposed to the recording medium, a slider that generates a positive or negative pressure by the air flow caused by the rotation of the recording medium. Further, light is applied to the recording medium from a light transmitting section formed on the slider. This structure makes it necessary to lead light to a light transmitting section of the slider from a light source arranged inside a magnetic recording/reproducing device.
For example, disclosed is an optical recording head including a mirror substrate having a mirror surface on an inclined surface, a slider formed of transparent SiO2, and an optical fiber, where light emitted from an optical fiber is reflected on the mirror surface, and is applied to the recording medium through the slider (Patent Document 1).
Another disclosed example is an optical recording head where an optical waveguide is used to lead light from the light source, and the light is applied to a minute opening of the slider through the reflection surface arranged on the optical waveguide (Patent Document 2).
Alternatively, a disclosed example is an optical recording head where an objective lens having an optical axis perpendicular to a recording medium is arranged on a slider, and light is condensed on the opening of the slider (Patent Document 3).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2003-6913
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2003-6912
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2001-14745